Read binary and pack/unpack functions ?

Read binary and pack/unpack functions ?

[Xavier Maillard]

Hi,

Iam trying to write a mode to read/write the Palm MemoDB file
based on the described format.

The MemoDB is well documented and thus, it is not that difficult
to build a parser against it.

Where iactually fail is at reading binary data from the file and
packing binary data into a more "neutral" format based on sexp.

Do you know any pack/unpack-like functions for GNU Emacs ?

Regards
-- 
Xavier

Re: Read binary and pack/unpack functions ?

[Kevin Rodgers]

Xavier Maillard wrote:
> Iam trying to write a mode to read/write the Palm MemoDB file
> based on the described format.
> 
> The MemoDB is well documented and thus, it is not that difficult
> to build a parser against it.
> 
> Where iactually fail is at reading binary data from the file and
> packing binary data into a more "neutral" format based on sexp.
> 
> Do you know any pack/unpack-like functions for GNU Emacs ?

Are you familiar with Emacs coding systems?

-- 
Kevin

Re: Read binary and pack/unpack functions ?

[maillaxa]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="us-ascii", Size: 1254 bytes --]


Kevin Rodgers a écrit :

> Xavier Maillard wrote:
> > Where iactually fail is at reading binary data from the file and
> > packing binary data into a more "neutral" format based on sexp.
> >
> > Do you know any pack/unpack-like functions for GNU Emacs ?
>
> Are you familiar with Emacs coding systems?

Yes I do and the problem is not with reading binary data but with
"mapping" bytes into something that reflect the binary file format
(header, data, ...).

In perl you have two valuable functions called pack and unpack that
takes a string and expands it out into a list of values. This is what I
am looking for in emacs lisp.

So is there anything similar ?

Regards,

Xavier

P.S: here is what I am ending up for reading (temporary and subject to
change. It basically load a file and try to read the first 72 bytes
from there (corresponding to the file header)

  (defun load-memodb (file-name)
   (save-excursion
     (set-buffer (create-file-buffer file-name))
     (erase-buffer)
     (if (fboundp 'set-buffer-multibyte)
	 (set-buffer-multibyte t))

     (let ((coding-system-for-read 'binary))
       (insert-file-contents file-name))
     (goto-char (point-min))
     (setq header (memo-read-bytes 72))))

Re: Read binary and pack/unpack functions ?

[Magnus Henoch]

Xavier Maillard <zedek@gnu.org> writes:

> Do you know any pack/unpack-like functions for GNU Emacs ?

See bindat.el.

Magnus

Re: Read binary and pack/unpack functions ?

[Johan Bockgård]

Magnus Henoch <mange@freemail.hu> writes:

> Xavier Maillard <zedek@gnu.org> writes:
>
>> Do you know any pack/unpack-like functions for GNU Emacs ?
>
> See bindat.el.

And the corresponding section in the manual, (info "(elisp)Byte Packing")

-- 
Johan Bockgård